Rubber hydrochloride



Patented Mar. 7

' UNITED {STATES PATENTOFFICE RUBBER maocimomna tion of Delaware No Drawing. Application March 29, 1939,

Serial No. 264,779

9-Claims. (Cl.

certain high-boiling photochemical inhibitors which' are substantially permanent and nonblooming and are especially advantageous in plasticized rubber hydrohalides.

- Rubber hydrohalides, such as rubber hydrochloride, have been known for many years and, in recent years, have become commercially useful. For some commercial uses oi such materials, it is necessary to employ stabilizers in order to retard the deterioration of the material caused or accelerated by the action of sunlight or other sources of ultra-violet light. It is the purpose of the present invention to provide new and improved photochemical inhibitors for use in rubber hydrohalides. It is a further object .of the invention to provide a new and improved rubber hydrohalide composition'containing such photochemical inhibitors. Other objects and advantages will appear as the description of the invention proceeds. The invention is particularly applicable to rubber hydrochloride.

Although photochemical inhibitors are known which will markedly increase the life of rubber hydrohalides exposed to ultra-violet light, most of these possess certain inherent characteristics which, in some instances, are very objectionable. For example, some of them are incompatible with the rubber hydrohalide and tend to blush or "bloom out. Some of them are fugitive so that, although they are effective in freshly prepared rubberhydrohalide, they are eventually lost, .and their inhibiting eifect with them. The compatibility and relative permanence of these photochemical inhibitors are markedly afiected by the use of various plasticizers in the rubber hydrohalide. For example, some inhibitors are entirely satisfactory in unplasticized rubber hydrohalides but tend to "bloom out in plasticized mixtures, i. e., they come, to the surface of the film or other article, forming a crystalline or oily deposit on the surface thereof. Plasticizers are desirable components of rubber hydrohalide mixes for the manufacture of many a1- ticles, particularly in the form of film, which are normally exposed to sunlight, e. g., window curtains, wrapping materia1s,,etc., in order to give a softer "feel to the rubber hydrohalide and increase its tear resistance; Thepreferred inhibitors of this invention are, therefore, those which are compatible withplasticized films or zoo-735i not form a bloom on such material on standing or ageing. The preferred plasticizers for such use are butyl stearate or other alkyl esters of fatty acids, dibutyl phthalate or other alkyl esters of phthalic acid or a hydrogenated phthalic acid, and ethyl abietate or other ester of an acid derived from a vegetable oil. Suitable plasticizers are propyl stearate, amyl stearate, hexyl stearate, heptyl stearate, decyl stearate, cyclohexyl stearate, glycol stearate, glyceryl stearate, ethyl oleate, butyl oleate, heptyl oleate, butyl palmitate, the propyl, amyl, heptyl, octyl, etc. esters of phthalic and hydrogenated phthalic acids, tributyl phosphate, triphenyl phosphate, and triphenyl thiophosphate. Such plasticizers, which impart tear-resistance to rubber hydrohalides, are. described in U. S. application Serial No. 102,223, filed September 23, 1936 inthe name of Calvert.

According to the invention, a new class of photochemical inhibitors for rubber hydrohalides has been discovered, the members of which have a number of very desirable characteristics. They efiectively resist the deteriorating efl'ect of light and the preferred members of the class are highly compatible with the rubber hydrohalide and are substantially permanent and non-fugitive in plasticized or unplasticized rubber hydrohalides.

' It has been known that primary amines will react with ethylene dihalides, such as ethylene dibromide, to produce substituted ethylene -diamines and piperazines according to the following equations:

CIHI

/NR+4HBr CaHi' These two reactions proceed simultaneously and both types of products are obtained. These products are not included in the present invention. In

addition, anumber of more complex reactions also take place and it is found, in carrying out the reaction, that a mixture of the products of these more complex reactions is also obtained. These complex products may conform to a variety of types. Thus, one moi of the amine reacts with one moi of ethylene dibromide according to the following equation:

other structures of rubber hydrohali des and do to Equation 3 reacted. with the substituted ethylene diamine resulting from Equation 1 gives a diethylene triamine in the following manner.

A triethylene tetramine may then be formed by any of the following processes (a) RNH-CQHr-N- OlHG-NE-R+BPCQ PNHR By successive reactions similar to those above,,

these ethylene poiyamines may build up to compounds of very high molecular weight,

Large cyclic compounds may be similarly formed by ioinder of the terminal secondary amino groups by reaction with ethylene bromide.

It is also possible that other types of reactions take place.

Compounds of the class type indicated above may also be prepared by reacting diethylene triamine, trietlrylene-tetramlne, etc. with a suitable alwl halide as illustrated by the following equa- ,Two hundred eighty-two parts (2.5 mols) of o-methyl cyclohexylamine were placed in a reactor equipped with a stirrer, a reflux condenser and a thermometer and the charge was heated to about 100 C. About 10% of the total charge of 192 parts (1.02 mol) of ethylene dibromide was run in slowly and was allowed to react. A portion (5-10% of the total) of the. caustic used to neutralize the hydrobromic acid formed in the reaction was then added. (This caustic solution was made by dissolving so parts of sodium hydroxide in 150 parts of water). The ethylene dibromide and caustic were thereafter alternately addedin small portions (5-10% of the total), allowing time for reaction after each addition, the reaction,'mixture being kept at a gentle reflux temperature of about 110 C. After about three hours, the lower aqueous layer containing sodium bromide was separated from the upper oily layer. The latter was distilled at 10-12 mm. pressure to obtain 86 parts of unreacted o-methyl cyclohexylamine, which was recovered below 170 C. 'A fraction amount to 214 parts was obtained at 170-270 C. This was redistilled at 10 mm. pressure to give 192 parts of a mixture of N,Ndi(o-methyl cyclohexyl) ethylene diamine and N,N'di(o-methy1 cyclohexyl) piperazine recovered over a temperature range of 180- I 215 C. At 215-259' C., 21 parts of a brownish, sirupy liquid were obtained. This was a mixture of high boilers" useful as photochemical inhibitors in rubber hydrohalides.

linux12 Two hundred two parts (2 mols) of tetrahydro furfurylamine, 188 parts (1 mol) of ethylene dibromide, and a solution of 90 parts of sodium hydroxide dissolved in 180 parts of water were reacted by the method outlined in Example 1.

The product was distilled at 10-12 mm. pressure 4 to yield the following fractions:

Parts (1) Up to 160 C 90 (2) 160-220 (2 74 (3) 220-270 C 53 As before, fraction 2 contained the ethylene diamine and piperazine derivatives. Fraction 3 contained high molecular compounds having the desired inhibiting properties.

Exams: 3

One hundred thirteen parts.(1 mol) of 3- then slowly added and the mixture was refluxed The folfor about one hour, after which the remainder of the caustic was added and the refluxing was continued for another hour. The oily reaction product was separated from the aqueous sodium bromide layer and was distilled at 10 mm. pressure. About 66 parts of the desired high-boiling constituents were obtained at 200300 C., and 10 parts of still higher boiling material were obtained as residue boiling above 300 C. Both of these, fractions were effective photochemical inhibitors.

Exaurrz 4 I Four hundred fifty-two grams (4 mols) of 0- methyl cyclohexylamine were reacted with 564 grams (3 mols) of ethylene dibromide as follows:

The amine was placed in a flask equipped with a stirrer, a reflux condenser, and a dropping funnel and heated to about 125 C. Ethylene bromide was then slowly added through the dropping funnel. -To prevent crystallization of amine hydrobroinide formed during the reaction, a few cc. of water were added through the condenser from time to time. When about half the ethylene dibromide'had been added, the mixture was heated to 120-130 C. for 10 minutes and about 90 grams of sodium hydroxide dissolved in 167 cc. of water were slowly added. The remainder of the ethylene dibromide was added as before and, after heating 10-15 minutes at 0., about grams of sodium hydroxide dissolved in 334 cc. of water were slowly added. The mixture was then maintained at 115-120 C. for one hour. The oily layer was separated from sure.

below 160 0.,

the aqueous layer and distilledat 6-7 mm. pres- Eighty grams of material were obtained 257 grams, consisting largely of N,N'di(o-methyl cyclohexyl) ethylene diamine, came over at ISO-205 C., and the residue weighed 205 grams. The residue was a brown oil, which. became viscous on cooling and consisted of amlxture of high boilers" useful as photochemical inhibitors. Distillation of the residue at 3-5 mm. pressure gave a major fraction boiling at 235-240 C., which was. also effective as a photochemical inhibitor. i

EXAMPLE 5 The N,N'di(o-methyl cyclohexyl) ethylene diamine obtained in Example 4 in the 257 gram fraction boiling at ISO-205 C. at 6-7 mm. pressure can be utilized in preparing succeeding from time to time to prevent crystallization. The

mixture was heated at 125-130 C. for 10-15 minutes and about A; of the caustic solution was slowly added. The remainder of the ethylene dibromide was then slowly added followed by the remainder of the caustic solution. The mixture was heated, with stirring, for one hour at 115-120? C. The oily layer was washed with water and distilled at 5-6 mm. pressure to obtain the following fractions:

Grams Below 160 C 24 160-205 C 378 Residue 262 The residue consisted of a mixture of the desired high-boiling photochemical inhibitors.

EXAMPLE 6 A mixture of 200 grams of N,N'di(o-methyl cyclohexyl) ethylene diamine, 135 grams of 0- methyl cyclohexylamine, 99 grams of ethylene dichloride, and 200 cc. of water was placed in a steel autoclave and heated at 200 for one-half hour. The reaction mixture was cooled to about 100 C., at which temperature it was completely liquid, and was treated with a mixture of 90 grams of sodium hydroxide and 100 cc. of water and boiled for one-half hour. The oily portion was then separated, washed with water and distilled at 5 mm. pressure to give the following fractions:

h The residue was a brown, viscous mixture of the for 1.0-15 minutes by a secondfportion of 564 grams,(3 mols) of ethylene dibromide and finally the remainder of the caustic solution. The mixture was stirred and heated at'115-l20 C. for one hour. The oily product was separated, washed withswater, and distilled at 5 min. pressurev to yield the following fractions:

r Grams Below 150 C 127 150-217 C 683.5 Residue 152 desired photo-chemical inhibitors.

Examts 8 Seventy-six parts ofdiethylene triamine, 310 parts of butyl bromide and a solution of 90 parts of sodium hydroxide dissolved in 200 parts of water were reacted by the method of Example 1. The reaction product was distilled at 4-5 mm. pressure, one hundred fifteen parts of the desired butyl diethylene triamines being obtained at 160-200 C.

The foregoing examples are illustrative of the materials useful in the invention and of methods of preparing them. Other alkylene polyhalides may be used in place of the ethylene dibromide and ethylene dichloride of Examples '1-7 and other primary aliphatic amines may be employed insteadof the amines there used.

Representative examples of other alkylene' polyhalides which may be used are n-propylene dibromide, 1,2-dibromopropane, 1-2, 1-3 and '1-4 dichlor or di-brom'butane, the dior tri-halogen derivatives of the pentanes, dichlorhydrin, di- (chlorethyl) ether, and homologues of these compounds. Of these materials, those compounds in which the alkylene groups are hydrocarbon i groups are preferred.

' benzyl amine and furfurylamine.

The residue was a brown, viscous oil possessing the desired photo-chemical inhibiting properties.

EXAMPLE 7 p Eight hundred grams (8.1 .mols) of cyclohcxylamine, mixed with 100 cc. of water, were treated with 564 grams (3 mols) of ethylene di-v bromide at a temperature rising from 100 C. to 120 C. Then about 5 3 of a solution of 540 grams Y of sodium hydroxide dissolved in 1000 cc. of Water was added, followed after heating and stirring Any primary aliphatic amine may be employed, including straight or branched chain amines, cycloaliphatic amines, such as cyclohexyamine, and ring substituted aliphatic amines, such as hexylamine, the heptylamines, the nonylamines,

the hexahydrophenetidines, the decahydronaphthylamines, the. ae-tetrahydro naphthylamines, allylamine, ,Bcyclohexy1 ethylamine, the aliphatic amino alcohols, B-phenyl ethylamine, etc.,

which may also contain various neutral or basic substituents such as amino, hydroxyl, alkoxy, aryloxy, etc. radicals. Those amines in which the aliphatic group is hydrocarbon are preferred.

When materials coming within the invention are prepared by the method represented by Equations 8 and 9 and Example 8, various polyalkylene polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, dipropylene triamine, dibutylene triamine, etc. may be reacted with any aliphatic halide such as the butyl bromides, the amyl bromides, benzyl bromide, cyclohexyl chloride and other aliphatic halides corresponding to the aliphatic amines listed in the preceding paragraph. Those compounds in which'the alkylene or aliphatic groups are hydrocarbon are preferred.

In view of the varied courses which the reaction may take, substantially any proportions of reactants may be employed. Also, the temperature, pressure and other conditions of the Further exv reaction may be varied\greatly while still obtaming materials coming within the invention.

. suitable for direct useand is a very effective photochemical inhibitor and constitutes a preferred iorm "oflthe invention.

Representative examples of the materials of K the invention were incorporated into rubber hydrochloride and samples in the form of thin films were exposed to artificial sunlight in a Fadeometer and to natural sunlight to determine the relative life of the protected film as compared with the life 01 a control containing no photochemical inhibitor but otherwise identical. A number of. the materials tested and the results obtained are listed in the following tables. Three formulations were employed; number 1 contained no plasticizer; number 2 contained l dibutyl phthalate and 2 9:, butyl stearate (based on the weight of rubber hydrochloride) number 3 contained'10% dibutyl phthalate. These same numbers are used in Table II below to indicate the formulations used with particular photochemical inhibitors in the tests. The inhibitors used in the tests are listed in Table I.

Table I Inhibitor Reaction product of- A N ,N' di(o-methyl cyclohexyl) ethylene dinmine+ ethylene dibromide (B. P. act-250 C. at 8 mm.) B o-Methyl cyclohexylamine+ethylene dibromide (B.

P. 250-260" C. at 12 mm.) C Tetrahydroiuriuryiamine+ethylene dibromide (B.

P. 2W-270' O. at 10-12 mm.) D x,y Hexahydro xylidenc+ethylene dibromido (B.

P. 200-300" C. 5 mm. Ev 3-methyl cyclohexylamlne+ethylene dibronude (B.

P. filo-300 C. at mm. F 3-methyl cyclohexylamine+ethyiene dlbromlde (B.

P. above 300 C. at 10mm. G 2,4'dimethyl cyclohexylamine+ethylone dibromide REM-300 O.at5mm. H '2,4dimethyl cyclohexylamine-t-ethylene dibromide (B. P. above 300 C. at 5 mm. I o-Methyl cyclohexylamine+ethylene dibromide (B.

P. 230-240 C. at 4-5 m.)

Table II Life as percent of control Inhibitor and formulation fif fi f g I Florida Fadeometer sunshine It will be seen from these data that the materials of the invention are very efiective photochemical inhibitors for rubber hydrohalides such as rubber hydrochloride. Moreover, as a class,

these materials are relatively more permanent than previously known inhibitors, this improvement being particularly noticeable in film containing added plasticizers such as butyl stearate and dibutyl phthalate.

What I claim is:

1 Rubber hydrochloride containing a photochemical inhibitor which is a reaction product of an alkylene polyhalide and a primary aliphatic amine, the said product having a boiling point higher than any alkylene polyamine and any N- aliphatic piperazine formed from the same starting materials.

2. Rubber hydrochloride containing a photochemical inhibitor which is a reaction product of I 3. Rubber hydrochloride containing, as a photochemical inhibitor, the-composite product obtained by reacting an alkylene polyhalide with a primary aliphatic amine and freeing the reaction product from any contained alkylene polyamines, piperazines and unreacted starting materials.

4. Rubber hydrochloride containing as a photochemical inhibitor, the composite product obtained by reacting an ethylene dihalide with a primary aliphatic amine and freeing the resultant reaction product from unreacted starting materials and by-product dii'aliphatic) ethylene diamine and N,N'di(aliphatic) piperazine.

. 5. Rubber hydrochloride containing a photochemical inhibitor which is a reaction product of an alkylene dihalide and a primary aliphatic amine, the said product containing more than two aliphatic substituted nitrogen atoms and having nitrogen to nitrogen linkages efi'ected through alkylene groups.

6. Rubber hydrochloride containing, as a photochemical inhibitor, a polyalkylene polyamine in which each of the amino nitrogen atoms contains one aliphatic substituent in addition to the connecting alkylene groups.

7. A fllm comprising rubber hydrochloride and a plasticizer which increases the tear-resistance oi the film and a photochemical inhibitor which is a reaction product of an alkylene dihalide and a primary aliphatic amine, the said product containing more than two aliphatic substituted nitro-- gen atoms and having nitrogen to nitrogen linkages efiected through alkylene groups and being sufliciently compatible with the plasticized rubber in which R and R: are aliphatic radicals, R1 is selected from the group consisting of hydrogen and aliphatic radicals, R3 and R4 are alkylene groups and a: is a. whole number.

WINFIELD SCOTT. 

